[welcome] Switch to QVector

- QVector is a better match with passing in QStringList, otherwise
   you end up dealing with Qt's int indexes vs. std::vector's uint
   indexes everywhere.
 - Introduce find()

src/modules/welcome/LocaleModel.cpp

@@ -21,10 +21,11 @@
 LocaleModel::LocaleModel(const QStringList& locales, QObject* parent)
     : QAbstractTableModel( parent )
 {
+    Q_ASSERT( locales.count() > 0 );
     m_locales.reserve( locales.count() );
 
     for ( const auto& l : locales )
-        m_locales.emplace_back( l );
+        m_locales.push_back( CalamaresUtils::LocaleLabel( l ) );
 }
 
 LocaleModel::~LocaleModel()
@@ -40,7 +41,7 @@ LocaleModel::columnCount( const QModelIndex& ) const
 int
 LocaleModel::rowCount( const QModelIndex& ) const
 {
-    return m_locales.size();
+    return m_locales.count();
 }
 
 QVariant
@@ -63,3 +64,33 @@ LocaleModel::data( const QModelIndex& index, int role ) const
             return QVariant();
     }
 }
+
+const CalamaresUtils::LocaleLabel& 
+LocaleModel::locale(int row)
+{
+    if ( ( row < 0 ) || ( row >= m_locales.count() ) )
+    {
+        for ( const auto& l : m_locales )
+            if ( l.isEnglish() )
+                return l;
+        return m_locales[0];
+    }
+    return m_locales[row];
+}
+
+int 
+LocaleModel::find(std::function<bool (const LocaleLabel &)> predicate) const
+{
+    for ( int row = 0; row < m_locales.count() ; ++row )
+    {
+        if ( predicate( m_locales[row] ) )
+            return row;
+    }
+    return -1;
+}
+
+int 
+LocaleModel::find(std::function<bool (const QLocale &)> predicate) const
+{
+    return find( [&]( const LocaleLabel& l ){ return predicate( l.locale() ); } );
+}

src/modules/welcome/LocaleModel.h

@@ -20,24 +20,40 @@
 #define WELCOME_LOCALEMODEL_H
 
 #include <QAbstractTableModel>
+#include <QVector>
 
-#include <vector>
 
 #include "utils/CalamaresUtilsGui.h"
 
 class LocaleModel : public QAbstractTableModel
 {
 public:
+    using LocaleLabel = CalamaresUtils::LocaleLabel;
+    
     LocaleModel( const QStringList& locales, QObject* parent = nullptr );
-    virtual ~LocaleModel();
+    virtual ~LocaleModel() override;
 
     int rowCount( const QModelIndex& parent ) const override;
     int columnCount( const QModelIndex& parent ) const override;
 
     QVariant data( const QModelIndex& index, int role ) const override;
 
+    /** @brief Gets locale information for entry #n
+     * 
+     * This is the backing data for the model; if @p row is out-of-range,
+     * returns a reference to en_US.
+     */
+    const LocaleLabel& locale( int row );
+    
+    /** @brief Searches for an item that matches @p predicate
+     * 
+     * Returns the row number of the first match, or -1 if there isn't one.
+     */
+    int find( std::function<bool(const QLocale&)> predicate) const;
+    int find( std::function<bool(const LocaleLabel&)> predicate) const;
+
 private:
-    std::vector< CalamaresUtils::LocaleLabel > m_locales;
+    QVector< LocaleLabel > m_locales;
 } ;
 
 #endif